The Department of Biology at the University of Southern Denmark invites applications for a position as postdoctoral researcher in aquatic microbial ecology and biogeochemistry, available for 2.5 years from January 2026, with possibility for extension. The position is associated to the ERC Synergy project RECLESS (Recycling versus loss in the marine nitrogen cycle: controls, feedbacks, and the impact of expanding low oxygen regions). RECLESS aims to predict how ongoing ocean deoxygenation impacts microbial nitrogen transformations and thereby the future availability of nitrogen to support oceanic primary production and carbon sequestration. The project involves researchers from the universities of Southern Denmark, Vienna, and Gothenburg, as well as Carnegie Science, and synergistically integrates innovative oceanographic, biogeochemical, ecophysiological, and model-based investigations.

The main research objective is the exploration and quantification of non-photosynthetic sources of oxygen in oxygen-depleted waters, so called dark oxygen production. Processes of this type were recently discovered in microbial cultures and could be important for microbial communities and element cycling in natural systems. However, the occurrence and significance of dark oxygen production in natural systems remain unknown.

A key task for the successful candidate is to develop and employ experimental techniques for the detection and quantification of dark oxygen production in marine oxygen minimum zone waters. Technical approaches include experimental incubations of water samples, high-sensitivity oxygen sensing, and, as a central component, oxygen stable isotope tracing and isotope ratio mass spectrometry. Participation in international oceanographic research cruises is an integral part of the position. The successful candidate will contribute actively to shaping the project. We further invite the candidate to suggest potential side projects depending on their specific interests.

We seek a candidate with a background in experimental (bio-)geochemistry, microbial ecology, or related fields, and with experience in field work. Experience with one or more of the above-mentioned techniques is desirable. The selected candidate will be associated to the research groups of Bo Thamdrup and Beate Kraft as part of the diverse and international Nordcee group at the department and will work closely together with associates from all RECLESS institutions.

The deadline for applications: 27 October 2025.

Please see the full call, including how to apply, on www.sdu.dk